There are no guarantees, but there have been portents. On one Saturday in July, San Diego got more rain than it got the entire month of January.

That same month, ESPN broadcaster Dan Shulman broke the news to baseball fans from underneath a golf umbrella: “For the first time in 20 years, a game has been postponed because of rain here in Anaheim.”

Storms headed for the California coast run into the Ridiculously Resilient Ridge, represented by the “H” in this graphic. (David Pierce/ KQED)

Strength in this case is measured by how much warmer surface temperatures are than normal, in the tropical Pacific. And this one looks to be about as strong as the legendary El Niño of 1997-98, which was the strongest on record, peaking at about 2.3 degrees Celsius above normal.

In the ocean, a spike of more than two degrees is like sticking a hot poker into the climate system. Pacific storms sucked up moisture from extremely warm equatorial waters and pretty much dumped it on California. San Francisco got double its normal rainfall that year.

Enter the Blob

But this time around, there are other things brewing in the Pacific: patches of freakishly warm water spread far and wide, up the California coast to the persistently warm vortex, hundreds of miles across, christened by climate scientists as “the Blob.”

“That is definitely the wildcard with this El Niño,” warns Bill Patzert, a climatologist at NASA’s Jet Propulsion Lab in Pasadena and an advisor to federal El Niño forecasters.

He says unlike in 1997, the Blob has been a fixture during the current drought. It’s essentially the sidekick of that “Ridiculously Resilient Ridge,” the stubborn bubble of high-pressure that’s been parked off the north coast for the past couple of years, diverting winter storms up and around California.

The “Blob” is associated with the persistent ridge of high pressure that has detoured the winter storm track around California. (NOAA)

“And so the question is, who wins in the battle of the Blob and the El Niño,” says Patzert, “and what impact that’ll have on rainfall on the West Coast of the U.S. this fall, into the winter.”

Patzert says if the Blob and its ridge dominate, we could wring less water out of this El Niño.

“What we’re having here is battling blobs!”

But not everyone’s on the edge of their seat.

“It doesn’t fit with my concept of how things work,” says Trenberth. On the contrary, he maintains, the presence of all this warm water — especially close to the coast — could mean heavier rains from the storms we do get.

A Mixed Blessing

“The potential in California for rains to be torrential this winter is quite high because of the warm water,” Trenberth says.

That’s because, as a general rule, the warmer the water, the more moisture gets picked up by the atmosphere and by any emerging storms.

“Those storms are apt to pick up moisture from any warm water that’s lying around all along the West Coast,” says Trenberth, “and it just feeds those storms.”

That would be both good and bad news. While the reservoirs refill, the rivers could easily overfill, causing flooding and landslides — much like in 1997-98. Trenberth will take that glass as half-full.

“The way things are shaping up it sure looks like an end to the drought to me,” he says, “depending on how you define the drought.”

Patzert agrees the current El Niño is looking like a monster — “Godzilla,” to use his favorite moniker. But he’s concerned the Blob and its ridge could become at least partial spoilers, blocking out storms from the northern Pacific, leaving the door open only for El Niño-driven storms from the tropics.

That could mean Southern California gets a soaking, but the northern part of the state — where most of the major reservoirs are — misses out.

“There is almost certainly going to be a dividing line,” says Stanford climate scientist Daniel Swain. “And it’s possible that dividing line could occur somewhere in Northern California.”

Patzert hopes that isn’t the case.

“If that happens, I’m definitely going to have to go into witness protection,” he frets, “because ‘my’ El Niño, the Great Wet Hope, will only deliver half the package.”

Whatever we get, it’s a package that won’t be delivered for at least three months, when California’s long-awaited “rainy” season is due.

Something to note is that the subtropical and polar jets are fundamentally different in terms of what drives them. Polar jet is driven by the polar vortex, and yes, the polar vortex is indeed extremely vulnerable to intrusion of heat from the ground and/or ocean, but the subtropical jet is instead driven by outflow from the tops of tropical thunderstorms and often routinely flows across waters far warmer than that Gulf of Alaska anomaly which is downright freezing by comparison.

It’s this other, lesser-known jet stream ― the one that is aimed across the jungles of southern Mexico, Central America, and Colombia during ENSO-neutral years ― that gets shoved north into southern California, northern Mexico, and the Desert Southwest when the tropical Pacific suddenly heats up and turns active as an El Niño event pans out. Last year, this jungle-drencher did actually make a brief appearance despite the blob’s existence: in December 2014, when the most drenching AR since Superstorm Melor hit. Meanwhile, Indonesia got absolutely zilch in the way of precip until about a week before QZ8501 took off, and right before the RRR returned, Winter Storm Frona hit, causing a noticeable cooling of local waters and dumping *snow* as low in elevation as Murrieta and Temecula. Proof that with regards to El Niño, coastal upwelling is actually a bad thing since it keeps that ridge-driving clockwise flow rotating. Simply put: cold wants to flow toward warm but gets deflected to the right by the Coriolis effect, and when cooling remains east of warming, it deflects in such a manner that clockwise flow keeps blocking in place. Therefore, Winter Storm Frona was in fact a precursor to the RRR’s return.

Then again, that clockwise flow that gets the ridge spinning/sinking is in itself driven by warming W/cooling E in Pacific, is it not? So what about the exact opposite? While NEPAC has indeed been warming, NWPAC, from the Bering Sea to Hawaii, has actually been cooling this year. That configuration is the exact opposite of the one that Winter Storm Frona+RRR induced, and when the Coriolis effect acts on cooling W/warming E, the result is actually counterclockwise rotation ― that in itself is the basic rule of cold PDO vs. warm PDO; therefore, it’s actually warm PDO that is most likely to enhance El Niño impacts, especially when combined with what is shaping up to be record cold AMO in Atlantic which tends to trap dipole-driving Arctic air masses smack over the middle of the Atlantic Ocean and therefore force the Greenland block to retrograde and build over the Hudson Bay instead, where it does little more than help El Niño out.

Gordon Lehman

The notion that the blob is creating the “ridiculously resilient ridge” is upside down. The ridge is causing the blob, both by keeping clouds away allowing solar warming of the NE Pacific and by virtue of its position somewhat east of normal more astride the coast. Much of the SST anomaly along the coast reflects a lack of upwelling. Upwelling is caused by northerly winds rotating around the ridge and down the coast when the ridge is in its normal position more out to sea.
If you go there you will not find a lot of people frolicking in that “warm” red water.
Furthermore, warm water does not create high pressure. Quite the opposite. Warm water warms the atmosphere above causing the warmer air to rise. This is defined as low pressure.

DarthCalumnious

Here they go making all of these predictions and they didn’t even think to ask Ted Cruz what he thinks! Does his opinion not even matter to these elitist climate scientists? What hubris!

Leslie Graham

Indeed. They should get Lord Monkton in to advise as well.
He’s the world’s leading expert on climate change after all.
This is shaping up as an interesting year or two climate wise. That ‘blob’ has been growing for a couple of years now and is a new phenomena. The only time that anything even close appeared was back in 1976 and even then it was tiny by comparison and gone in a few months. The entire northern Pacific is on average 0.97C warmer than ‘normal’ – if we have a ‘normal’ these days. The Indian Ocean is also much warmer than average and the sea off Japan is at ridiculous temperatures now. The Japanese heatwave put another 12000 in hospital just in the last week. The Med is also much warmer and Egypt is suffering a big heat wave too. So is Iraq and Iran. Oh – and north Australia. And of course most of Europe. And the Ukraine. And a large part of sout America. And Alaska ……. actualy – is there anywhere that is cooler than normal?
Oh yes – north east USA and a strip of the north Atlantic. That proves Globull warming is a hokes I guess.

thx1104

Well, It’s three months later and Northern California has gotten very little rain while Southern California has indeed been soaked at least once. October rainfall in San Jose is 1/10 of an inch, whereas normal rainfall would be 8/10 of an inch. The once in a 20 year El Nino is being completely rescinded by the high pressure “Blob”.

Timothy Fitzpatrick

Very well done article!~!

Author

Craig Miller

Craig is KQED's science editor, specializing in weather, climate, water & energy issues, with a little seismology thrown in just to shake things up. Prior to his current position, he launched and led the station's award-winning multimedia project, Climate Watch. Craig is also an accomplished writer/producer of television documentaries, with a focus on natural resource issues.

Support of KQED Science is provided by HopeLab, S. D. Bechtel, Jr. Foundation, The Dirk and Charlene Kabcenell Foundation, The Vadasz Family Foundation, John S. and James L. Knight Foundation, Gordon and Betty Moore Foundation, Smart Family Foundation and the members of KQED.